How PlayStation Works

The innovative PlayStation controller attracted attention with its winged shape and its buttons.

The controller is the primary user interface for the PlayStation. And just as the gamepad that came with the original Nintendo Entertainment System was a radical departure from previous controllers, the PSX controller changed the rules again. With its winged shape and abundance of well-positioned buttons, it is user-friendly and yet powerful.

The standard PSX controller has 14 buttons! They include:

four buttons arranged as a directional pad on the top left

Start and Select buttons in the top middle

four action buttons on the top right

two action buttons on the front left

two action buttons on the front right

Although each button can be configured to perform a specific and distinctive action, they all work on the same principle. In essence, each button is a switch that completes a circuit when it is pressed. A small metal disk beneath the button is pushed into contact with two strips of conductive material on the circuit board inside the controller. While the metal disk is in contact, it conducts electricity between the two strips. The controller senses that the circuit is closed and sends that data to the PSX. The CPU compares that data with the instructions in the game software for that button, and triggers the appropriate response. There is also a metal disk under each arm of the directional pad. If you're playing a game in which pushing down on the directional pad causes the character to crouch, a similar string of connections is made from the time you push down on the pad to when the character crouches.

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Newer Dual Shock PSX controllers have analog joysticks on them, as well as the standard buttons. These joysticks work in a completely different way from the buttons described above. Two potentiometers (variable resistors) are positioned at right angles to each other below the joystick. Current flows constantly through each one, but the amount of current is determined by the amount of resistance. Resistance is increased or decreased based on the position of the joystick. By monitoring the output of each potentiometer, the PSX can determine the exact angle at which the joystick is being held, and trigger the appropriate response based on that angle. In games that support them, analog features like these allow for amazing control over gameplay.

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Another feature of the Dual Shock controller, actually the reason for its name, is force feedback. This feature provides a tactile stimulation to certain actions in a game. For example, in a racing game, you might feel a jarring vibration as your car slams into the wall.

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The Dual Shock controller uses force feedback to simulate the action in the game.

Force feedback is actually accomplished through the use of a very common device, a simple electric motor. In the Dual Shock controller, two motors are used, one housed in each handgrip. The shaft of each motor holds an unbalanced weight. When power is supplied to the motor, it spins the weight. Because the weight is unbalanced, the motor tries to wobble. But since the motor is securely mounted inside the controller, the wobble translates into a shuddering vibration of the controller itself. Now let's take a closer look at how the controller talks to the PSX.

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Here's what each pin does:

DATA - This pin carries the signal that the controller sends to the PSX each time a button is pressed. It is an 8-bit serial transmission.

COMMAND - This pin is used by the PSX to send information to the controller. Such information might trigger the motors in a Dual Shock controller at the proper moment. It also uses an 8-bit serial transmission.

Not used

GROUND

POWER - This pin supplies 5 volts to the controller from the PSX.

SELECT - This pin is used by the PSX to notify the controller of incoming data.

CLOCK - This pin carries a synchronizing signal sent from the PSX to the controller.

Not used

ACKNOWLEDGE - This pin sends a signal to the PSX from the controller after each command that is received on Pin 2.